Rain Harvesting First Flush Advanced 4" Downpipe Diverter Kit – WDDP120 | Electronic Release Valve & Catch-All Tee
Product Details
Protect your rainwater quality at the source with the Rain Harvesting First Flush Advanced 4" Downpipe Kit (WDDP120). The first rush of water off any roof carries the highest concentration of dust, leaf litter, bird droppings, and airborne pollutants. This kit diverts that contaminated "first flush" away from your tank so only cleaner water is stored.
Two upgrades set the Advanced apart from a standard T-junction diverter. The patented Catch-All high-flow tee stops fast-moving dirty water from skipping past the diverter entrance during heavy downpours — a common failure point on basic units. And the adjustable release valve lets you dial in how often diverted water drains: flush more frequently to prioritize water quality, or less frequently to maximize stored volume.
The transparent tapered exit funnel makes inspection easy and channels sediment into the drain flow to resist buildup and clogging, and a rapid-exit valve lets you fully empty the chamber whenever needed. Built from UV-stabilized, impact-resistant PVC for years of reliable outdoor service, it cuts into any vertical 4" (100mm) round downpipe and resets automatically after each rainfall.
Ideal for residential and light-commercial rainwater harvesting — garden irrigation, laundry, toilet flushing, and potable use with appropriate downstream filtration.
Model: WDDP120
Application: Suits 4" (100mm) round downpipes
Material: UV-stabilized, impact-resistant PVC
Capacity: Adjustable based on diverter pipe length
Mechanism: Ball and seat system with slow-release drain valve
Installation Orientation: Vertical inline installation
✅ Benefits
Cleaner Tank Water – Diverts roof dust, debris, bird droppings, and other pollutants away from the tank
Adjustable Diverter Volume – Customize the pipe length to match roof size and rainfall volume
Reliable Reset – Ball and seat mechanism automatically resets after each rainfall
Durable and UV Resistant – Built for long-lasting performance in outdoor environments
Simple Maintenance – Easily accessible components for cleaning and inspection
Installation Overview
Cut into the vertical 4" downpipe at the desired height
Install the T-junction and diverter chamber
Attach the ball seat, ball, and end cap with the release valve
Adjust diverter pipe length based on required first flush volume
Shipping & Handling
Package Dimensions: 32" L × 12" W × 10" H
Shipping Weight: Approximately 8 lbs
Packaging: Individually boxed with fittings and installation guide
Delivery Method: Ships via standard ground service
Rain Harvesting Downpipe First Flush Advanced Water Diverter, part# WDDP120 diverts more contaminants and gives you greater control over water volume. The First Flush Diverters are installed using a T junction or high flow inlet to which the diversion chamber is fitted. As the chamber fills with the initial dirty water, a ball rises until it seals the inlet, allowing the rest of your rainwater, which is much cleaner, to flow directly to your tank.